Common mode voltage enumeration in a battery pack

ABSTRACT

An apparatus and method for these embodiments of the present invention, useful in manufacturing for example, includes a plurality of battery modules serially intercoupled together, each module including a housing with an anode connector and a cathode connector, each housing including a memory for storing a module identifier and wherein an anode connector of a first module is coupled to a cathode connector of a second module; and a processing system, coupled to each the module, for determining a plurality of positional attributes of each the module, one positional attribute associated with each the module of the plurality of modules, the processing system writing an ID into the memory of each particular module responsive to the associated positional attribute for the particular module.

BACKGROUND OF THE INVENTION

The invention relates generally to battery packs for electric vehiclesand industrial applications, and more specifically to improvements inintelligent battery packs for simplifying manufacturing and detection ofbattery pack condition during operation.

Commercial grade high performance battery packs are commonly assembledfrom individual cells packaged into modules. There is typically sometype of on-board intelligence incorporated into individual modules tomonitor and control particular operational characteristics of eachmodule, and collectively of the battery pack. This intelligence may bequite rudimentary, or quite sophisticated, based upon needs. Dependingupon battery chemistry and application among other factors, various dataare gathered by a battery monitoring system.

For enhancing safety and performance, it is preferred that monitoring beperformed in real-time. Important information is collected by theon-board intelligence and gathered by the battery monitoring system fromthe individual modules. The individual modules are uniquely identifiedand addressed during the monitoring process.

Current manufacturing of battery packs includes serial interconnectionof the several modules making up the particular battery pack. There areadvantages in manufacturing and maintenance in knowing the geographiclocation of a particular module in the battery pack. In someapplications, the individual modules are distributed throughout thedevice and it is even more advantageous to know which particular moduleis which and where it is physically located.

There are many prior art systems for uniquely identifying and addressingspecific devices like the modules. Some of these systems include uniquecodes incorporated into a module during manufacturing, other systemsprovide for DIP switches, jumpers, or other mechanical solution to set adesired address. There are prior art systems that use electrical systemsto gate communication to a next device in a daisy-chain until thatdevice is identified. These have downsides, particularly, a) theyrequire daisy chain interface rather than a bussed interface, and b)they require additional circuitry to gate the communication signals tothe next device, which may not be compatible with all communicationinterfaces due to impedance, voltage range, isolation requirements, andthe like.

Such systems burden the manufacturing process with requirements forensuring unique IDs, as well as mapping the IDs into the geographicchain of the final assembly. Errors in the manufacturing are possibleand create difficulties in locating and correcting operational problemsindicated by the on-board intelligence. It can be difficult, if at allpossible, to disambiguate modules in the event that non-unique IDs havebeen used. Locating and servicing a module from among many modules,modules that may be distributed geographically, that has been improperlymapped in the geographic string may unduly negatively impact the qualityand efficiency of the servicing process.

What is needed is a module enumeration system that does not undulyburden manufacturing or restrict electrical and module interconnectdesign due to drawbacks with existing designs as discussed above.

BRIEF SUMMARY OF THE INVENTION

The present invention provides for a module enumeration system that doesnot unduly burden manufacturing or restrict electrical and moduleinterconnect design due to drawbacks with existing designs. The systemand method provide for automatically, dynamically, and efficientlyassigning unique IDs to the individual modules of the battery pack whileaccurately geographically mapping them in the battery pack. Thepreferred implementation uses a dynamic measurement of one or morepositional attributes of said plurality of battery modules, and thenusing the positional attribute(s) to assign a unique ID (e.g., anaddress) to each battery module. This address, once dynamicallyassigned, remains statically fixed based upon the positional attributes.One example of a positional attribute is a common mode voltage of eachmodule when serially electrically intercoupled with the other modules.In some implementations, the positional attributes include additionalgeographic attributes such as where the particular module is physicallyinstalled (e.g., behind the glove compartment or in the trunk). Thissolution offers advantages in both manufacturing andmonitoring/servicing of the battery pack. Manufacturing is able toassign a reference (e.g., the unique ID) to the manufactured pack bydetermining dynamically across all the modules to determine all thepositional attributes and then assigning the IDs based upon an orderingof the positional attributes. This makes manufacturing much easier.

Monitoring/servicing may use embodiments of the present invention bydetermining a current (real-time) positional attribute of a module andthen comparing it to a reference positional attribute of that module.The reference positional attribute is implied by the ID associated withthe module as it was dynamically assigned based upon a positionalattribute available at manufacture/installation. The referencepositional attribute may thus be derived from the ID. When the currentpositional attribute has a predetermined relationship to the referencepositional attribute (e.g., a mismatch) then the module is flagged.Further management, monitoring, servicing may be desired to address acondition resulting in the flagged predetermined relationship. Themonitoring is dynamic and may implemented continually in real-time orperiodically as desired.

Disclosed is an apparatus and method for these embodiments of thepresent invention. An apparatus, useful in manufacturing for example,includes a plurality of battery modules serially intercoupled together,each module including a housing with an anode connector and a cathodeconnector, each housing including a memory for storing a moduleidentifier (ID) and wherein the anode connector of a first module iscoupled to the cathode connector of a second module; and a processingsystem, coupled to each module, for determining a plurality ofpositional attributes of each module, one positional attributeassociated with each module of the plurality of modules, the processingsystem writing the ID into the memory of each particular moduleresponsive to the associated positional attribute for the particularmodule.

A method, useful for manufacturing for example, includes (a) determininga plurality of positional attributes across a plurality of seriallyintercoupled battery modules, each of the modules including a memory forstoring a module identifier (ID); and (b) writing the ID into the memoryof each particular module responsive to the associated positionalattribute for the particular module.

An apparatus, useful for monitoring/servicing for example, includes aplurality of battery modules serially intercoupled together, each moduleincluding a housing with an anode connector and a cathode connector,wherein an anode connector of a first module is coupled to a cathodeconnector of a second module, and wherein each module includes areference developed from a determination of a reference positionalattribute of the plurality of modules; a processing system, coupled toeach module, for determining a plurality of current positionalattributes for the plurality of battery modules, one current positionalattribute associated with each module of the plurality of modules; acomparator, coupled to the processing system, for comparing a referencepositional attribute for a particular reference associated with aparticular one battery module to the current positional attribute of theparticular one battery module; and a monitor, coupled to the comparator,for flagging the particular one battery module when a predeterminedrelationship exists between the reference positional attribute and thecurrent positional attribute.

A method, useful for monitoring/servicing for example, includes (a)determining dynamically a plurality of current positional attributesacross a plurality of serially intercoupled battery modules; and (b)comparing, for a particular one of modules, the current positionalattribute with a predetermined reference developed from a dynamicdetermination of a reference positional attribute of the plurality ofmodules; and (c) flagging the particular one battery module when apredetermined relationship exists between the reference positionalattribute and the current positional attribute.

Module identification is important when a battery pack is in operationfor a number of reasons including: 1) It helps associate measured datawith a physical location within the battery pack; 2) It informs servicepersonnel which module to replace in case of a identified problem withinthe battery pack; and 3) It facilitates addressing within communicationschemes. The present invention provides a dynamic identificationsolution to assignment of static module identifiers, along withattendant benefits derived from this implementation including dynamicservice value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a battery assembly according to thepresent invention;

FIG. 2 is a flowchart of an ID assignment determination process; and

FIG. 3 is a flowchart of an ID confirmation determination process.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to battery packs for heavy application,such as for electric passenger vehicles and industrial application. Forexample, the present invention may be used in a Tesla Motors' Roadsteror Model S sedan. While applicable to many heavy uses, theimplementation in a battery pack is described in detail below for makingthe invention easier to understand by reference to a specific example.In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be apparent, however, to one skilled in the art, that the presentinvention may be practiced without some or all of these specifieddetails and may be applied to any battery pack assembly for example. Insome instances, well known process steps of determining/measuring commonmode voltages have not been described in detail in order to notunnecessarily obscure the present invention.

The following description is presented to enable one of ordinary skillin the art to make and use the invention and is provided in the contextof a patent application and its requirements. Various modifications tothe preferred embodiment and the generic principles and featuresdescribed herein will be readily apparent to those skilled in the art.Thus, the present invention is not intended to be limited to theembodiments shown but is to be accorded the widest scope consistent withthe principles and features described herein.

FIG. 1 is a schematic diagram of a battery assembly 100 according to thepresent invention. Battery assembly 100 includes a plurality of seriallycoupled battery modules 105 _(i) and a battery monitoring system 110coupled to each battery module 105 _(i). A connector 115 couples ananode of battery module 105 _(i) to a cathode of battery module 105_(i+1).

Connector 115 is an electrical coupler and may be implemented in any ofseveral ways, including a fuse, electrical conductor, direct connection,or the like.

Particular specific details of the construction and assembly of abattery module vary according to application and chemistry, so thefollowing description is provided as one of many possibleimplementations. Each battery module 105 _(i) includes a housing havinga collection of individual lithium-ion cells 120 (individually or insubassemblies). Each module 105 _(i) also includes a processingsub-system 125, specific to application and battery chemistry, foracquiring and reporting data. Processing sub-system includes a memoryfor saving/storing desired information. The data that is collected andreported may include performance, status, and other information forenhancing safety, operation, and maintenance of the modules 105 _(i) andbattery assembly 100.

A network 130 couples each processing sub-system 125 to batterymonitoring system 110. Network 130 is shown as a one-to-many wiredcoupling of battery monitoring system 110 to each processing sub-system125 though other implementations are possible including wirelessparallel coupling, a ring coupling, or a hybrid combination.

Each processing sub-system 125 may be implemented as a microcomputersolution having a microcontroller/microprocessor and memory or it may bemore rudimentary combinatorial logic for monitoring desired data orstate information within each module 105 i. However implemented, eachprocessing sub-system 125 includes an identifier (ID) that serves as aunique address in battery assembly 100. There are many addressingsystems that may be used, the present invention dynamically assigns eachID and writes it, during the manufacturing/installation phase, intoprocessing sub-system 125. The dynamic assignment of the static ID ismade in such a way that the assigned IDs reflect positional/geographicpositioning (e.g., the positional/geographic information may berelative, absolute, or include some of both characteristics).

For purposes of the present discussion, the term positional attributeincludes a determinable ordering characteristic of the module wheninstalled into a pack having two or more modules. The positionalattribute may indicate relative or absolute ordering of a serialcoupling of the modules. In the preferred embodiment, a positionalattribute includes a common mode voltage of each module. In someinstances, geographic positioning is also desired and refers to aspecific physical location of a particular battery module 105 _(x)(either relative or absolute) in the series couplings of modules 105_(i). In some applications, it may be preferred to use some otherpositional attribute besides common mode voltage, or in addition tocommon mode voltage.

Depending upon the specific application, it may be useful to know that amodule with a particular ID is the N^(th) module from a particular endof the series coupling. In some implementations, battery modules aredistributed in various locations in the vehicle or machine. For example,it may be that the N^(th) module 125 _(N) is located behind the glovecompartment. By knowing a particular ID, and knowing that the particularID is assigned to module 125 _(N), and that the N^(th) module is locatedin the glove compartment, it is easy for a user to determine that theparticular module with that particular ID is behind the glovecompartment. These are included in the definition of positionalattribute and geographic location terms.

This is in contrast to conventional systems which provide formanufacturing to set the ID, using jumpers, DIP switches, software, orthe like. It is a drawback that the settings may not be set properly toreflect the desired ID to be assigned, or that the assigned ID will notbe absolutely or relatively unique. Absolutely unique refers to a uniqueID that is not matched across any batter pack assembly (or set of suchassemblies), while relatively unique refers to an ID not matched withina battery pack. Even in the event that the intended ID assignment ismade and that assignment is unique, manufacturing would still need tocreate a manual mapping of the geographic location of the modules whenthis feature is desired. This manual mapping lends itself to thepotential for mis-mapping which may be, in some cases, worse than nomapping. And the manual mapping adds additional effort and cost, so itmay not be implemented even when it is otherwise useful.

In the preferred embodiment, the dynamic assignment is made by using acommon mode voltage of each battery module 105 _(i) determined relativeto a ground that is common to the modules. The more robust the ground,the better the determined common mode voltages will accurately reflectthe positional attributes. In a series coupling of uniform batterymodules, when the voltage across a battery pack varies from +V_(bat)/2to −V_(bat)/2, the common mode voltage at each module is an incrementalchange over the battery voltage range.

A common situation in the art of network communications is arbitrationof various network events. In the present context, one particular eventis the dynamic assignment of the static reference IDs across all themodules upon assembly (manufacture) of the battery pack. As notedherein, each module is dynamically assigned an address, but uponpower-up, each module has an undefined (or pre-defined) ID that couldlead to collisions on the network bus. There are many ways ofpotentially resolving these conflicts upon power-up to permit thedynamic assignment of reference IDs based upon the real measuredpositional attributes.

The preferred embodiments provide for a varying power-up delay of eachmodule when the assembled battery pack is powered. The particular delayis a function of the positional attribute. That is, in the case when thepositional attribute is a common mode voltage, the delay of each moduleis responsive to the particular common mode voltage. A “first” (e.g.,one with the highest or lowest voltage) module is powered up, has itsreference ID determined and assigned. A “second” module is next poweredup. The process continues until all modules have been powered up andreceived a reference ID.

FIG. 2 is a flowchart of an ID assignment process 200. Process 200 is apreferred embodiment for dynamically assigning the static reference IDs.Step 205 of process 200 determines (e.g., measures) positionalattributes (e.g., the common mode voltages) across modules 105 _(i) ofbattery system 100. Next, step 210 of process 200 orders the determinedcommon mode voltages in a positional/geographic order. The geographicorder, in the preferred embodiment, geographically orders voltage (andits associated module) starting at one “end” of the series coupling inincreasing (or decreasing) order. The above-described process ofpowering up the modules in an order determined by positional attributes(e.g., the common mode voltages) is one way of determine positionalattributes and ordering them. Other solutions are possible and may beused in addition to or in lieu of the solutions described herein.

Next, step 215 of process 200 assigns an ID to each module responsive tothe ordered determined common mode voltages. For example, battery module125 ₁ (e.g., the battery module with the lowest common mode voltage) isassigned ID₁. Next at step 220, process 200 writes the assigned IDs intoprocessing sub-system 125. These static IDs are dynamically assigned,and assigned after the modules have been coupled and, in some cases,after installation.

When the IDs are dynamically derivable based upon positional attributesand/or geographic position, another aspect of the present invention isavailable to users. Particularly available to monitoring and servicingusers. For example, there are conditions of battery modules 105,connectors 115, and of battery system 100, that may alter apost-manufacture/post-install determination of common mode voltages.Should a module fail or have other electrical connection problems, or aconnector fail, in particular ways, the measured common mode voltages ofa battery system 100 is compared to the assigned ID in the module chain.The common mode voltages are continually monitored by the modulemonitors, during service and during operation (they may, of course, beperiodically monitored as well). When the comparison of the currentcommon mode voltage differs from common mode voltage implied by theassociated reference ID, then there may be a situation that needsresolution.

It is one use of this aspect of the invention that an installationconfirmation test may be made to determine whether determined positionalattributes (e.g. common mode voltages) determined at an assembly timeare different from common mode voltages determined after battery system100 is installed. A difference may reflect a mis-installation that iscorrected earlier in the manufacturing process. Module monitors may runa post-installation check (for monitoring/diagnostic) or duringservicing as the common mode voltages are always available. A batterymodule that has a common mode voltage different from what it had duringmanufacturing/installation may indicate a potential problem. Because theoriginal static reference ID was dynamically assigned based upongeographic positioning, it is a simple matter for manufacturing to focusadditional diagnostic/trouble-shooting on the suspect battery module.

FIG. 3 is a flowchart of an ID confirmation determination process 300.Process 300 is a preferred embodiment for dynamically evaluating thebattery modules of a battery pack. For example, the process may use thedynamically determined static IDs for detection of possible flaggedconditions. Step 305 of process 300 determines (e.g., measures) thecommon mode voltages across modules 105 _(i) of battery system 100.Next, step 310 of process 300 orders the determined common mode voltagesin a geographic order based upon positional attributes (e.g., commonmode voltages). The geographic order, in the preferred embodiment,geographically orders voltage (and its associated module) starting atone “end” of the series coupling in increasing (or decreasing) order.The above-described process of powering up the modules in an orderdetermined by positional attributes (e.g., the common mode voltages) isone way of determine positional attributes and ordering them. Othersolutions are possible and may be used in addition to or in lieu of thesolutions described herein.

Next, step 315 of process 300 implies an expected ID for each moduleresponsive to the ordered determined positional attributes (common modevoltages). For example, battery module 125 ₁ (e.g., the battery modulewith the lowest common mode voltage) is determined that it should haveID₁. Next at step 320, process 200 reads the stored IDs from the memoryof processing sub-system 125. These stored IDs were dynamicallyassigned, and assigned after the modules had been serially electricallycoupled and, in some cases, after installation of the pack (andindividual modules of the assembled pack).

Step 325 compares the measured positional attribute with an impliedpositional attribute derived from the reference ID and step 330 flagsany discrepancies from comparison step 325. (This could be done as wellby implying a current ID from the current positional attribute andcomparing the implied ID with the reference ID.) A discrepancy mayindicate a short, an open, or other condition affecting the determinedpositional attribute (e.g., the common mode voltages). Flagging isperformed when the current positional attribute has a predeterminedrelationship to the a reference positional attribute (e.g., amis-match). Thus, these discrepancies could indicate a reason foradditional diagnostic, servicing, maintenance, or other operationincluding deactivation of any potentially misbehaving battery module.

The system, method, and computer program product described in thisapplication are embodied in hardware; e.g., within or coupled to aCentral Processing Unit (“CPU”), microprocessor, microcontroller, Systemon Chip (“SOC”), or any other programmable device. Additionally, thesystem, method, and computer program product may be embodied in software(e.g., computer readable code, program code, instructions and/or datadisposed in any form, such as source, object or machine language)disposed, for example, in a computer usable (e.g., readable) mediumconfigured to store the software. Such software enables the function,fabrication, modeling, simulation, description and/or testing of theapparatus and processes described herein. For example, this can beaccomplished through the use of general programming languages (e.g., C,C++), GDSII databases, hardware description languages (HDL) includingVerilog HDL, VHDL, AHDL (Altera HDL) and so on, or other availableprograms, databases, nanoprocessing, and/or circuit (i.e., schematic)capture tools. Such software can be disposed in any known computerusable medium including semiconductor, magnetic disk, optical disc(e.g., CD-ROM, DVD-ROM, etc.) and as a computer data signal embodied ina computer usable (e.g., readable) transmission medium (e.g., carrierwave or any other medium including digital, optical, or analog-basedmedium). As such, the software can be transmitted over communicationnetworks including the Internet and intranets, virtual private networksand/or local area networks. A system, method, and computer programproduct embodied in software may be included in a semiconductorintellectual property core (e.g., embodied in HDL) and transformed tohardware in the production of integrated circuits. Additionally, asystem, method, and computer program product as described herein may beembodied as a combination of hardware and software, e.g., CPU, PROM,ROM, RAM and the like.

In the description herein, numerous specific details are provided, suchas examples of components and/or methods, to provide a thoroughunderstanding of embodiments of the present invention. One skilled inthe relevant art will recognize, however, that an embodiment of theinvention can be practiced without one or more of the specific details,or with other apparatus, systems, assemblies, methods, components,materials, parts, and/or the like. In other instances, well-knownstructures, materials, or operations are not specifically shown ordescribed in detail to avoid obscuring aspects of embodiments of thepresent invention.

A “computer-readable medium” for purposes of embodiments of the presentinvention may be any medium that can contain, store, communicate,propagate, or transport the program, or expanded content includingdynamic information including score, performance, grade, bookmarkfeatures, instructions (all or a portion thereof) for use by or inconnection with the instruction execution system, apparatus, system ordevice. The computer readable medium can be, by way of example only butnot by limitation, an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system, apparatus, system, device,propagation medium, or computer memory.

A “processor” or “process” includes any human, hardware and/or softwaresystem, mechanism or component that processes data, signals or otherinformation. A processor can include a system with a general-purposecentral processing unit, multiple processing units, dedicated circuitryfor achieving functionality, or other systems. Processing need not belimited to a geographic location, or have temporal limitations. Forexample, a processor can perform its functions in “real time,”“offline,” in a “batch mode,” etc. Portions of processing can beperformed at different times and at different locations, by different(or the same) processing systems.

Reference throughout this specification to “one embodiment”, “anembodiment”, or “a specific embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention and notnecessarily in all embodiments. Thus, respective appearances of thephrases “in one embodiment”, “in an embodiment”, or “in a specificembodiment” in various places throughout this specification are notnecessarily referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics of any specificembodiment of the present invention may be combined in any suitablemanner with one or more other embodiments. It is to be understood thatother variations and modifications of the embodiments of the presentinvention described and illustrated herein are possible in light of theteachings herein and are to be considered as part of the spirit andscope of the present invention.

Embodiments of the invention may be implemented by using a programmedgeneral purpose digital computer, by using application specificintegrated circuits, programmable logic devices, field programmable gatearrays, optical, chemical, biological, quantum or nanoengineeredsystems, components and mechanisms may be used. In general, thefunctions of the present invention can be achieved by any means as isknown in the art. Distributed, or networked systems, components andcircuits can be used. Communication, or transfer, of data may be wired,wireless, or by any other means.

It will also be appreciated that one or more of the elements depicted inthe drawings/figures can also be implemented in a more separated orintegrated manner, or even removed or rendered as inoperable in certaincases, as is useful in accordance with a particular application. It isalso within the spirit and scope of the present invention to implement aprogram or code that can be stored in a machine-readable medium topermit a computer to perform any of the methods described above.

Additionally, any signal arrows in the drawings/Figures should beconsidered only as exemplary, and not limiting, unless otherwisespecifically noted. Furthermore, the term “or” as used herein isgenerally intended to mean “and/or” unless otherwise indicated.Combinations of components or steps will also be considered as beingnoted, where terminology is foreseen as rendering the ability toseparate or combine is unclear.

As used in the description herein and throughout the claims that follow,“a”, “an”, and “the” includes plural references unless the contextclearly dictates otherwise. Also, as used in the description herein andthroughout the claims that follow, the meaning of “in” includes “in” and“on” unless the context clearly dictates otherwise.

The foregoing description of illustrated embodiments of the presentinvention, including what is described in the Abstract, is not intendedto be exhaustive or to limit the invention to the precise formsdisclosed herein. While specific embodiments of, and examples for, theinvention are described herein for illustrative purposes only, variousequivalent modifications are possible within the spirit and scope of thepresent invention, as those skilled in the relevant art will recognizeand appreciate. As indicated, these modifications may be made to thepresent invention in light of the foregoing description of illustratedembodiments of the present invention and are to be included within thespirit and scope of the present invention.

Thus, while the present invention has been described herein withreference to particular embodiments thereof, a latitude of modification,various changes and substitutions are intended in the foregoingdisclosures, and it will be appreciated that in some instances somefeatures of embodiments of the invention will be employed without acorresponding use of other features without departing from the scope andspirit of the invention as set forth. Therefore, many modifications maybe made to adapt a particular situation or material to the essentialscope and spirit of the present invention. It is intended that theinvention not be limited to the particular terms used in followingclaims and/or to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include any and all embodiments and equivalents falling within thescope of the appended claims. Thus, the scope of the invention is to bedetermined solely by the appended claims.

1. An apparatus, comprising: a plurality of battery modules seriallyintercoupled together, each module including a housing with an anodeconnector and a cathode connector, wherein an anode connector of a firstmodule is coupled to a cathode connector of a second module, and whereineach said module includes a reference developed from a staticmeasurement of a reference positional attribute of said plurality ofmodules wherein said reference positional attribute of each particularmodule identifies a particular reference location of said particularmodule in said serially intercoupled plurality of battery modulesrelative to other battery modules of said plurality of modules; aprocessing system, coupled to each said module, for determining aplurality of current positional attributes for said plurality of batterymodules, one current positional attribute associated with each saidmodule of said plurality of modules wherein said current positionalattribute of each particular module identifies a particular currentlocation of said particular module in said serially intercoupledplurality of battery modules relative to other battery modules of saidplurality of modules; a comparator, coupled to said processing system,for comparing a reference positional attribute for a particularreference associated with a particular one battery module to saidcurrent positional attribute of said particular one battery module; anda monitor, coupled to said comparator, for flagging said particular onebattery module when a predetermined relationship exists between saidreference positional attribute and said current positional attributewherein existence of said predetermined relationship indicates that saidparticular current location of said particular one module is differentfrom said particular reference location.
 2. The apparatus of claim 1wherein said positional attribute includes a common mode voltageassociated with each said module.
 3. The apparatus of claim 2 whereinsaid reference includes an ID unique among IDs of said plurality ofbattery modules.
 4. The apparatus of claim 3 wherein said positionalattribute includes a geographic location reference of said particularmodule in said serial intercoupling.
 5. The apparatus of claim 4 whereinsaid geographic location reference is determined based upon an orderingof said associated common mode voltages.
 6. A method, the methodcomprising the steps of: (a) determining dynamically a plurality ofcurrent positional attributes for each of a plurality of seriallyintercoupled battery modules wherein said current positional attributeof a particular battery module identifies a particular current locationof said particular battery module in said serially intercoupledplurality of battery modules relative to other battery modules of saidplurality of modules; and (b) comparing, for a particular one of saidplurality of modules, said current positional attribute with apredetermined reference developed from a dynamic determination of areference positional attribute of said plurality of modules wherein saidreference positional attribute of a particular battery module identifiesa particular reference location of said particular battery module insaid serially intercoupled plurality of battery modules relative toother battery modules of said plurality of modules; and (c) flaggingsaid particular one battery module when a predetermined relationshipexists between said reference positional attribute and said currentpositional attribute wherein existence of said predeterminedrelationship indicates that said particular current location of saidparticular one module is different from said particular referencelocation.
 7. The method of claim 6 wherein said positional attributeincludes a common mode voltage associated with each said module.
 8. Themethod of claim 7 wherein said reference includes an ID unique among IDsof said plurality of battery modules.
 9. The method of claim 8 whereinsaid positional attribute includes a geographic location reference ofsaid particular module in said serial intercoupling.
 10. The method ofclaim 9 wherein said geographic location reference is determined basedupon an ordering of said associated common mode voltages.
 11. A method,the method comprising the steps of: (a) determining dynamically aplurality of current positional attributes for each of a plurality ofserially intercoupled battery modules after installation into a vehiclewherein said current positional attribute of a particular battery moduleidentifies a particular current location of said particular batterymodule in said serially intercoupled plurality of battery modules insaid vehicle relative to other battery modules of said plurality ofmodules; and (b) comparing, for a particular one of modules, saidcurrent positional attribute with a predetermined reference developedfrom a dynamic determination of a reference positional attribute of saidplurality of modules wherein said reference positional attribute of aparticular battery module identifies a particular reference location ofsaid particular battery module in said serially intercoupled pluralityof battery modules relative to other battery modules of said pluralityof modules wherein said reference positional attribute was developedbefore said plurality of serially intercoupled battery modules wereinstalled into said vehicle; and (c) flagging said particular onebattery module when a predetermined relationship exists between saidreference positional attribute and said current positional attributewherein existence of said predetermined relationship indicates that saidparticular current location of said particular one module is differentfrom said particular reference location.